The engine air system of a gas turbine engine requires extraction of compressed air from the gaspath to support cooling flow and bearing pressurization in the engine, among other things. The air pressure needed requires extraction of the bleed air from a suitable location, such as mid-way through the centrifugal stage of the compressor. An aerodynamic design of the bleed geometry helps minimize losses in the bleed system and preserve the flow structure through the impeller.
A known bleed system uses a plurality of discrete bleed holes to extract flow through the impeller shroud into the bleed cavity. Air is drawn from the gaspath at the discrete locations of the holes on the shroud. While such a bleed system is operational, improvements are desired in various regards.